header {
  width: 100%;
  ul {
    list-style: none;
    padding: 0;
    li {
      float: left;
      margin: 10px 20px;
      padding: 0 10px;
      line-height: 1.5em;
      background: #ddfdf8;
      border: 1px solid lightseagreen;
      color: white;
      cursor: pointer;
    }
    &:after{
      content: "";
      display: block;
      height: 0;
      clear: both;
    }
  }
}
